RE: [query] smartreflex: No PMIC hook to init smartreflex

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> -----Original Message-----
> From: Vishwanath Sripathy [mailto:vishwanath.bs@xxxxxx] 
> Sent: Thursday, January 27, 2011 7:56 PM
> To: Menon, Nishanth; Premi, Sanjeev
> Cc: linux-omap@xxxxxxxxxxxxxxx
> Subject: RE: [query] smartreflex: No PMIC hook to init smartreflex
> 
> Nishant,
> 
> > -----Original Message-----
> > From: linux-omap-owner@xxxxxxxxxxxxxxx [mailto:linux-omap-
> > owner@xxxxxxxxxxxxxxx] On Behalf Of Menon, Nishanth
> > Sent: Thursday, January 27, 2011 3:06 PM
> > To: Premi, Sanjeev
> > Cc: linux-omap@xxxxxxxxxxxxxxx
> > Subject: Re: [query] smartreflex: No PMIC hook to init smartreflex
> >
> > Sanjeev,
> >
> > On Tue, Jan 25, 2011 at 20:55, Premi, Sanjeev <premi@xxxxxx> wrote:
> > > While building the kernel at 2.6.37, i see this warning 
> for omap3evm -
> > with omap3630:
> > >
> > > Power Management for TI OMAP3.
> > > sr_init: No PMIC hook to init smartreflex <-- THIS IS THE WARNING.
> > > smartreflex smartreflex.0: omap_sr_probe: SmartReflex driver
> > initialized
> > > smartreflex smartreflex.1: omap_sr_probe: SmartReflex driver
> > initialized
> > > SmartReflex Class3 initialized
> > >
> > > In the code, i see this comment:
> > >  /*
> > >  * sr_init is a late init. If by then a pmic specific API is not
> > >  * registered either there is no need for anything to be done on
> > >  * the PMIC side or somebody has forgotten to register a PMIC
> > >  * handler. Warn for the second condition.
> > >  */
> > >  if (sr_pmic_data && sr_pmic_data->sr_pmic_init)
> > >  sr_pmic_data->sr_pmic_init();
> > >  else
> > >  pr_warning("%s: No PMIC hook to init smartreflex\n", __func__);
> > >
> > > But, I couldn't find any place where PMIC is being registered.
> >
> > This is a harmless warning (ideally, we should remove the 
> pr_warning).
> >  the intent here is to have hook for pmic_init which could be
> > populated for custom PMICs which may need "something additional" for
> > Smart reflex enablement. if you look at the sr_pmic_data - 
> it just has
> > a single api for pmic_init
> >
> > e.g. in the case of TWL4030/5030, we might need to set the bit to
> > switch mode from I2C1 to I2C_SR - e.g. the patch from Shweta[1]
> >
> > if Smartreflex AVS was the *only* mechanism in the system, we could
> > have hooked pmic_init to this bit setting. but since the 
> system can do
> > voltage scaling (VP forceupdate/vc bypass) independent of SR AVS
> > block, the patch in [1] does initialization independent of
> > sr_pmic_data->pmic_init which makes sense.
> >
> > in short, my 2cents: the warning is probably something we should
> > remove from the code.
> As you mentioned, incase of TWL4030/5030, we do not need any 
> hook. However
> if some other PMIC is used that genuinely needs this hook, 
> then shouldn't
> SR throw up this warning? As SR module is independent of 
> PMIC, it cannot


I possibly see different arguments from your description:
1) This is hook is not needed for TWL4030/5030.
   But still, still hook is needed for another PMIC.

2) It is okay to warn user for non-existent hook that is not
   really needed... in hope that there could be a different PMIC.

3) Despite saying that SR is independent of PMIC, we assume it as
   default and don't go thru the "plugin" route.

Something seems to be missing in the argument. I haven't been able
to spend more time on this since last mail (also reason for late
response); but:

1) When user adds the hook - for different PMIC, this warning/info
   would go away. But not for current default systems.

2) By keeping TWL4030 as default, we are possibly not telling the
   person keen on replacing the PMIC what should be done?

If SR is really PMIC independent, then warning is right only if
TWL4030 is also 'plugged-in' as any other PMIC is expected to be.

> distinguish them. So I feel this warning should be present probably
> reworded better like "No PMIC hook registered to init 
> smartreflex. Either
> this PM IC does not need SR init or PMIC hook is missing".

This wording - as is - would again be misleading.

~sanjeev

> Vishwa
> >
> > [1] http://marc.info/?l=linux-omap&m=129584746102725&w=2
> > Regards,
> > Nishanth Menon
> > --
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